Composite orthopedic implant having a low friction material substrate with primary frictional features and secondary frictional features

ABSTRACT

An orthopedic implant comprising a substrate material adapted to provide the orthopedic implant. The implant has a primary friction area located on or integral with the substrate material. The primary friction area defining an engagement surface having a primary frictional feature. A secondary friction area is located on or integral with the engagement surface and defining a second frictional feature. The primary friction area and the secondary friction area defining a friction interface zone between the orthopedic implant and at least one bone. The secondary friction area increases a friction of the engagement surface and modulus of elasticity to enhance the frictional engagement between the engagement surface and the at least one bone.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to provisional U.S. ApplicationSer. No. 61/365,912 filed Jul. 20, 2010, to which Applicant claims thebenefit of the earlier filing date. This provisional application isincorporated herein by reference and made a part hereof.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a composite orthopedic implant having a lowfriction material substrate with primary frictional features andsecondary frictional features.

2. Description of the Related Art

The placement of spinal implants between vertebrae is a common surgicalprocedure. A number of such spinal implants, which are generally hollowand box-shaped or cylindrical, have been developed. One risk of suchprocedures is the post-operative expulsion or dislocation of theimplanted device. There is a need to increase the frictional forcesbetween the device and the bone surface.

The most advantageous material for the manufacture of intervertebralspinal implants is thermoplastic polymer, of which the most commonlyused is polyetheretherketone (PEEK). This material has provenbiocompatibility with human tissue and is biomechanically strong enoughto withstand long-term cyclical loading as occurs within the spine. Thistype of material has a modulus of elasticity similar to bone, reducingthe probability of bone subsidence which can occur with harder metallicimplants. A significant problem, however, with the use of such polymericspinal implants is inherent low levels of bone-device surfaceinteraction. Machined or molded polymeric materials tend to haverelatively high levels of lubricity, elasticity, and smoothness whichconspire to reduce friction at the bone-device interface. This canresult in undesirably low frictional forces between bone and theimplanted device. Several parties have attempted to address this issueby adding large frictional features to the polymer implant. Thesefeatures are typically exemplified by surface teeth of various designs.Although surface teeth increase interface friction somewhat, theunderlying challenges of lubricity, smoothness and elasticity remain.

What is needed, therefore, is a polymer implant that builds upon thecurrent state of the art.

SUMMARY OF THE INVENTION

One object of an embodiment is to provide simple frictional featuresthat add a metallic surface material which has features of lowlubricity, low elasticity and secondary frictional features. Such adesign will maintain the desirable biomechanical properties of thepolymeric implant itself while addressing frictional shortcomings at thebone-device interface. Physical properties of the metallic surface canbe further optimized using dispersed deposition techniques onto thepolymeric substrate.

A composite bone-device interface used, in its preferred embodiment, inan orthopedic implant for the support of spinal vertebrae. The interfaceis manufactured from, in its preferred embodiment, a combination ofbiocompatible materials, which comprise a bone-device interface zone.The interface zone comprises a relatively low friction polymericsubstrate material and primary frictional features. The primaryfrictional features further comprise a high-friction surface materialcontaining secondary frictional features.

One object of one embodiment is to provide a primary friction feature incombination with a secondary friction feature.

Another object is to provide an embodiment where the primary frictionfeature is integral with the body and comprises the same material as thebody, such as a polymeric substrate, whereas the secondary frictionfeature which is integral with, applied to, deposited on or otherwiseadhered to the primary friction feature is of a different substrate,such as a metal or a metal alloy.

Still another object is to provide a surgical implant having improvedfrictional engagement at the bone-implant engaging interfaces.

Still another object is to provide an embodiment wherein the secondaryfrictional features are plasma vapor depositions on the primaryfrictional features.

Still another embodiment is to provide an implant having a body withboth primary frictional features and secondary frictional features.

Yet another object of one embodiment is to provide primary and secondaryfrictional features in the form of teeth or serrations that can beregular or irregular in shape, discontinuous or continuous or otherwisehave different or the same shape or configuration with respect to eachother.

Another object of an embodiment is to provide secondary frictionalfeatures in the form of elongated teeth that are situated on or integralwith the primary frictional features, which in one embodiment are alsoteeth, and which are either regular and uninterrupted or irregular andinterrupted.

In one aspect, one embodiment comprises an orthopedic implant comprisinga substrate material adapted to provide the orthopedic implant, aprimary friction area located on or integral with the substratematerial, the primary friction area having a primary surface having aprimary frictional feature and a secondary friction area located on orintegral with the primary surface and defining a secondary frictionalfeature, the primary friction area and the secondary friction areadefining a friction interface zone, the secondary friction areaincreasing a friction of the primary surface to enhance the frictionalengagement between the primary surface and at least one bone.

In another aspect, another embodiment comprises an orthopedic implantcomprising a body comprising a composite material, a first friction areasituated between the body and bone of a patient when the orthopedicimplant is implanted in the patient and a second friction areaassociated with the first friction area for directly engaging the bone,each of the first and second friction areas for improving a frictionalengagement between the bone and the orthopedic implant.

In yet another aspect, another embodiment comprises a method forimproving a frictional interface between an implant and bone of apatient, comprising the steps of processing a body to comprise a primaryfriction feature, and processing the body to comprise a secondaryfriction feature directly on the primary friction feature.

These and other objects and advantages will be apparent from thefollowing description, the accompanying drawings and the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of one embodiment;

FIG. 1A is sectional view taken along the line 1A-1A in FIG. 1;

FIG. 2 is an enlarged view of a portion of the implant shown in FIG. 1showing details of the primary friction feature and secondary frictionfeature;

FIG. 3 is a perspective view of the enlargement shown in FIG. 2;

FIG. 4 is a sectional view taken along the line 4-4 in FIG. 5illustrating the secondary friction feature in the form of a deposit orcoating on the primary friction feature;

FIG. 5 is a view of another embodiment showing the primary frictionfeature as teeth and the secondary friction feature as a deposit orcoating;

FIGS. 6A-6B is a view of another embodiment of the invention showing theelongated teeth that are interrupted or spaced in the direction of arrowA;

FIG. 7 is a view of another embodiment of the invention similar to FIG.5;

FIGS. 8A-8B are views of the secondary friction features having a curvedor serpentine shape;

FIGS. 9A-9B illustrate an embodiment wherein the primary frictionfeatures have a curved or serpentine shape while the secondary frictionfeatures have a generally linear (FIG. 9A) shape or a curved (FIG. 9B)shape;

FIGS. 10A-10B illustrate another embodiment similar to FIGS. 4 and 5wherein the deposit or coating is selectively placed;

FIG. 11 illustrates the primary friction feature and secondary frictionfeature in the form of teeth having different shapes, pitches, pitchthickness and the like; and

FIGS. 12A-12B illustrate embodiments wherein the primary frictionfeature or secondary friction feature are interrupted (FIG. 12A) alongtheir longitudinal length and wherein the primary friction feature isnot interrupted along its longitudinal length, but the secondaryfriction feature is interrupted (FIG. 12B).

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now to FIGS. 1-5, a first embodiment of an orthopedic implant10 is shown. The orthopedic implant 10 comprises a body 12 that isadapted to provide or define the orthopedic implant 10. In theillustration being described, the orthopedic implant 10 could be aspinal implant, such as a cage, plate or other implant wherein surfacesof the orthopedic implant 10 engage, for example, bone of a patient. Inone application, the orthopedic implant 10 is situated between adjacentvertebrae (not shown) of a patient. In the illustration being described,the orthopedic implant 10 comprises the body 12 made from a substrate orcomposite material, such as a polymeric material. The polymeric materialmay be a thermoplastic material, such as polyetheretherketone (PEEK).The substrate or composite material has a low coefficient of frictionwith bone.

The orthopedic implant 10 defines an orthopedic cage 11 in thisillustration having a plurality of walls 14 a, 14 b, 14 c and 14 d. Thewalls 14 a and 14 c have windows 18 and 20 as shown. The orthopedicimplant 10 has a plurality of walls 21 that define tool apertures 22 forreceiving a tool (not shown) for placement of the orthopedic implant 10,for example, between adjacent vertebrae (not shown) in the patient.

The implant 10 further has a first end 12 a and a second end 12 b. Asbest illustrated in FIGS. 2-5, note that the orthopedic implant 10comprises a first or primary friction area, layer or feature 24 appliedto, adhered to or integrally formed on each ends 12 a and 12 b. In theillustration, the body 12 defines a cage 11 that has four bone-engagingareas or surfaces 12 a 1, 12 a 2, 12 b 1 and 12 b 2.

In the illustration being described, the first or primary friction area,layer or feature 24 comprises or is adapted to define a first pluralityof teeth or serrations 26 which are integrally formed in the surfaces 12a 1, 12 a 2, 12 b 1 and 12 b 2 as shown. The body 12 is machined,molded, extruded, centered, cast or has a deposited substrate that isapplied to the body 12 to provide or define the first or primaryfriction area, layer or feature 24. Although not shown, it should beappreciated that the first or primary friction area, layer or feature 24may be separate from and non-integral with the body 12, for example, butthat is secured thereto by a weld, bond adhesive or other type offixation. In the illustration being described relative to FIGS. 1-3, thefirst or primary friction area, layer or feature 24 comprises the firstplurality of teeth or serrations 26 that are integral with the body 12and both are made of the same polymeric substrate, such aspolyetheretherketone (PEEK). Alternatively, the body 12 could be madefrom a polymeric substrate while the first or primary friction area,layer or feature 24 may comprise a metallic or metallic alloy that isapplied or, adhered to or otherwise affixed or secured to the body 12.After the orthopedic implant 10 is implanted into the patient, the firstor primary friction area, layer or feature 24 becomes situated betweenthe body 12 and the bone of the patient, such as the adjacent vertebra(not shown).

As mentioned earlier, the first or primary friction area, layer orfeature 24 comprises the first plurality of teeth or serrations 26 thatare integral with both ends 12 a and 12 b of the body 12, and each ofthe areas or surfaces 12 a 1, 12 a 2, 12 b 1 and 12 b 2 have the firstplurality of teeth or serrations 26. For ease of illustration, portionsof the first plurality of teeth or serrations 26 on the surface 12 a 2are shown fragmentarily and enlarged in FIGS. 2 and 3, but it should beunderstood that the first plurality of teeth or serrations 26 of thefirst or primary friction area, layer or feature 24 on the otherportions of surface 12 a 2 and on the other surfaces 12 a 1, 12 b 1 and12 b 2 are substantially the same in this embodiment.

The orthopedic implant 10 further comprises a second or secondaryfriction area, layer or feature 28 associated with the first or primaryfriction area, layer or feature 24. In the illustration being described,the second or secondary friction area, layer or feature 28 is appliedto, deposited on, adhered to, bonded, located on or integral with thefirst or primary friction area, layer or feature 24 as shown. In theillustration being shown in FIGS. 1-3, the first or primary frictionarea, layer or feature 24 and the second or secondary friction area,layer or feature 28 cooperate to define a plurality of frictioninterface zones 30 (FIGS. 1-1A).

The second or secondary friction area, layer or feature 28 is appliedto, deposited on, adhered to, located on or adhered to teeth surfaces,such as surfaces 26 a and 26 b (FIG. 2) of each of the first pluralityof teeth or serrations 26 on the surfaces 12 a 1, 12 a 2, 12 b 1 and 12b 2 where the orthopedic implant 10 engages bone and increases afriction between each of the first plurality of teeth or serrations 26and the bone of the patient. It has been found that the enhancedfrictional engagement facilitates maintaining the position of theorthopedic implant 10 in the patient. For example, it is desirable thatthe cage 11 illustrated in FIGS. 1 to 5 not move after it is implantedin the patient, and the second or secondary friction area, layer orfeature 28 enhances the frictional engagement between the first orprimary friction area, layer or feature 24 and the bone of the patientto prevent or minimize such movement.

The first or primary friction area, layer or feature 24 comprises afirst or primary friction feature in the form of the first plurality ofteeth or serrations 26, and the second or secondary friction area, layeror feature 28 comprises a second or secondary friction feature thatenhances the orthopedic implant's 10 friction interface zone 30. In theembodiment of FIGS. 1-3, 6A-6B, 7, 8A-8B, 9A-9B, 11 and 12A-12B, thesecond or secondary friction area, layer or feature 28 comprises asecond plurality of teeth or serrations 32 integral with, deposited on,adhered to or otherwise applied to one or more of the first plurality ofteeth or serrations 26 as shown. The body 12, the first or primaryfriction area, layer or feature 24 and the second or secondary frictionarea, layer or feature 28 is manufactured from, in its preferredembodiment, a combination of bio-compatible materials, including but notlimited to, at the friction interface zone 30.

In the illustration being described, the second or secondary frictionarea, layer or feature 28 may comprise a microscopically and/ormacroscopically rough or porous surface, which enhances the frictionalengagement between the first or primary friction area, layer or feature24 and the bone of the patient. The rough surface may be provided by,for example, sand blasting, coating, plasma spraying, vapor deposition,adhering a frictional layer, peening or even laser shock peening.

The secondary friction features may comprise a machined, molded,extruded, sintered or deposited surface material. In the illustration ofFIGS. 4-5, 10A and 10B, the deposited surface material may comprise acoating or deposition that is sprayed onto, melted to or otherwiseapplied or adhered to the primary surface 26 a of the first or primaryfriction area, layer or feature 24. In the embodiment shown in FIGS. 4,5, 7 and 10A-10B, the coating or deposition is a plasma vapor depositionapplied using a conventional plasma vapor deposition process. Thus, itshould be understood that the second or secondary friction area, layeror feature 28 may be integral with, welded to, machined into, adheredto, deposited on or otherwise affixed, processed or applied to the firstor primary friction area, layer or feature 24.

In the illustrations being described, the body 12, the first or primaryfriction area, layer or feature 24 and the second or secondary frictionarea, layer or feature 28 may be made from the same bio-compatiblematerial or one or more of them can comprise or be made from differentbio-compatible materials. In one embodiment, each of the body 12 and thefirst or primary friction area, layer or feature 24 are made of abio-compatible polymeric substrate, such as polyetheretherketone (PEEK),while the second or secondary friction area, layer or feature 28 iscomprised of a metal or metallic alloy. In the embodiments of FIGS. 1-5,the body 12 and the first or primary friction area, layer or feature 24are integral and monolithically formed and are made from the same PEEKmaterial, while the second or secondary friction area, layer or feature28 is a metallic material, metal, or metallic alloy, such as titanium,cobalt or associated alloys. It should be understood that the body 12,first or primary friction area, layer or feature 24 and the second orsecondary friction area, layer or feature 28 could be the same material,such as a polymer, a metal or metal alloy or different materials.

The body 12 and the first or primary friction area, layer or feature 24comprise the polymeric substrate have a relatively low modulus ofelasticity and/or a modulus of elasticity equivalent to bone while thesecond or secondary friction area, layer or feature 28 has a highermodulus elasticity and has a modulus of elasticity that is higher thanbone. It should be understood, however, that both of the first orprimary friction area, layer or feature 24 and/or the second orsecondary friction area, layer or feature 28 could comprise a relativelyhigh modulus of elasticity or a modulus of elasticity that is higherthan bone if desired.

Thus, at least one or both of the first or primary friction area, layeror feature 24 or the second or secondary friction area, layer or feature28 may comprise a relatively high coefficient of friction with bone,while the underlying substrate or body 12 and the first or primaryfriction area, layer or feature 24 may comprise a relatively low modulusof elasticity and low coefficient of friction relative to bone. In theembodiment of FIGS. 1-5, the second or secondary friction area, layer orfeature 28 comprises a higher coefficient of friction and higher modulusof elasticity compared to the first or primary friction area, layer orfeature 24 and body 12 which facilitate the frictional engagement andlocking of the orthopedic implant 10 in the patient, such as between thepatient's vertebra.

Thus, it should be understood that while the body 12 and the first orprimary friction area, layer or feature 24 and the second or secondaryfriction area, layer or feature 28 may be made from the same materialshaving the same coefficient of friction and modulus of elasticity, theycould comprise different materials which have either the same ordifferent coefficients of friction and/or the same or different moduliof elasticity. Also, the first or primary friction area, layer orfeature 24 and the second or secondary friction area, layer or feature28 could be different materials and their respective modulus ofelasticity and coefficients of friction relative to bone may bedifferent as mentioned earlier.

Again, it should be understood that one advantage of the embodimentsbeing described is that they enhance the frictional engagement of theorthopedic implant 10 when it is implanted in the patient. Thus, theorthopedic implant 10 having the first or primary friction area, layeror feature 24 comprising the second or secondary friction area, layer orfeature 28 will comprise a higher modulus of elasticity and highercoefficient of friction compared to bone.

Advantageously, the polymers or polymeric materials used in the past maybe utilized in manufacturing the body 12 and the shortcomings of suchmaterials can be used to provide the orthopedic implant 10 having thebody 12 that has relatively high levels of lubricity, elasticity andsmoothness, but which have been adapted, machined or processed asprovided herein to provide relatively high modulus of elasticity andhigh coefficients of friction at the orthopedic implant 10-boneinterface by providing the first or primary friction area, layer orfeature 24 with the second or secondary friction area, layer or feature28 as described herein.

As mentioned earlier, the first or primary friction area, layer orfeature 24 may be machined, molded, integral extruded, sintered ordeposited onto the body 12. The first or primary friction area, layer orfeature 24 may be separate from or integral with the body 12 asmentioned earlier. Likewise, the second or secondary friction area,layer or feature 28 may be machined, molded, extruded, sintered ordeposited directly on the first or primary friction area, layer orfeature 24 and may also be separate from or integral with it. Forexample, the second or secondary friction area, layer or feature 28 maybe sprayed onto, deposited on, melted to, or otherwise applied to oradhered to the first plurality of teeth or serrations 26 surfaces, suchas surfaces 26 a and 26 b of each of the first plurality of teeth orserrations 26, and/or on each surface 12 a 1, 12 a 2, 12 b 1 and 12 b 2having the first or primary friction area, layer or feature 24, therebyenhancing the frictional engagement between the orthopedic implant 10and the bone. As mentioned earlier, the second or secondary frictionarea, layer or feature 28 may be deposited on these surfaces using aplasma vapor deposition process.

Returning to the embodiment of FIGS. 1-3, the first or primary frictionarea, layer or feature 24 comprises the first plurality of teeth orserrations 26 that have peaks and valleys in cross section and areelongated, with each tooth or serration being generally the same inshape and dimension. Likewise, the second or secondary friction area,layer or feature 28 is defined by the second plurality of teeth orserrations 32 that are machined into, integral with, adhered to orapplied directly to the surfaces 26 a and 26 b of the first plurality ofteeth or serrations 26 as illustrated in FIGS. 1-3. In the illustrationbeing described, the plurality of teeth 32 are thermally bonded,adhered, impregnated, embedded on or in into the teeth 26. For ease ofillustration, FIG. 2 shows bonding of the teeth or serrations 32 toteeth or serrations 26 with an adhesive 37, but it should be understoodthat the teeth may be adhered by other means. As with the firstplurality of teeth or serrations 26, the second plurality of teeth orserrations 32, such as teeth 32 a and 32 b in FIG. 2, may each comprisegenerally the same shape and be elongated along the longitudinal axisand continuous as shown in FIG. 3. In other words, the first and secondpluralities of teeth or serrations 26 and 32 may be regular in shape.

Note that the first plurality of teeth or serrations 26 are elongatedand comprise surfaces 26 a and 26 b comprising the rows or strips 33 ofthe second plurality of teeth or serrations 32. The rows or strips 33are made of metal or a metal alloy, such as titanium or otherbiocompatible substance capable of providing a high-friction layer, inthe illustration and adhered to or overmolded with the body 12.

In the illustration, the orthopedic implant 10 is inserted into thepatient and the first or primary friction area, layer or feature 24 andthe second or secondary friction area, layer or feature 28 on surfaces12 a 1, 12 a 2, 12 b 1 and 12 b 2 frictionally engage bone to secure theorthopedic implant 10 in the patient.

FIGS. 6-9B and 11-12B illustrate other embodiments with like parts beingidentified with the same part numbers except that one or more legends orprime marks (“′”) have been added to distinguish the various embodimentsof these figures.

Note that the first plurality of teeth or serrations 26′ in FIG. 11comprises different cross-sectional shapes and sizes. Thus, the firstand second pluralities of teeth or serrations 26′ and 32′ may be adaptedto be irregular in shape, and the first plurality of teeth or serrations26′ in FIG. 11 could comprise different cross-sectional shapes andsizes. For example, note that tooth 26 c′ has a different shape and sizecompared to tooth 26 d′.

Likewise, the shape or size of each individual tooth, such as teeth 32a′ and 32 b′ (FIG. 11) of the second plurality of teeth or serrations32′ may be different. Thus, the individual teeth in each of the firstand second plurality of teeth or serrations 26′ and 32′ could be thesame or have different shapes, and they could have different pitches,depths, widths and the like and will be described later herein.

As mentioned, while the embodiment in FIGS. 1-3 illustrate that each ofthe first plurality of teeth or serrations 26 and the second pluralityof teeth or serrations 32 are generally regular and uninterrupted asshown, but it should be understood that either at least one of both ofthe first and second pluralities of teeth or serrations 26 and 32 may benon-elongated and interrupted. For example, FIG. 12A illustrates thatboth the first plurality of teeth or serrations 26″ and the secondplurality of teeth or serrations 32″ that are situated on or integralwith each of the first plurality of teeth or serrations 26′ are notcontinuous and are interrupted along their longitudinal axis. FIG. 12Billustrates an embodiment where only the second plurality of teeth orserrations 32″ is interrupted, but not the first plurality of teeth orserrations 26″. Alternatively, while the embodiments shown in FIGS. 12Aand 12B illustrates first and second pluralities of teeth or serrations26″ and 32″ being interrupted along their longitudinal axis, it shouldbe understood that there may be a mixture of interrupted anduninterrupted teeth if desired.

FIGS. 6A-6B illustrate still another embodiment wherein the secondplurality of teeth or serrations 32″″ are spaced or interrupted in thedirection of arrow A in FIG. 6A-6B as shown. In this regard, it shouldbe appreciated that one or both surfaces of each tooth, such as surfaces26 a″″ and 26 b″″ in FIGS. 6A-6B, are shown as having at least one or aplurality of the second plurality of teeth or serrations 32″″ mountedthereon or integral therewith. They are separately shown, but it shouldbe understood that either one or both surfaces of the plurality of teethor serrations 26″″, such as surfaces 26 a″″ and 26 b″″, may either haveor not have less teeth or one or more of the second plurality of teethor serrations 32″″.

Still other embodiments are shown in FIGS. 8A-8B and 9A-9B wherein thesecond plurality of teeth or serrations 32″″ are shown in a curved orserpentine and non-linear shape. It should be understood that the firstplurality of teeth or serrations 26″″ could also be provided in aserpentine or curved shape, with the second plurality of teeth orserrations 32″″ as shown. Although not shown, the first plurality ofteeth or serrations 26″″ could be generally serpentine or curved (FIGS.9A-9B) with the second plurality of teeth or serrations 32″″ also havinga serpentine or curved shape. FIGS. 8A-8B illustrate the first teeth orserrations 26 being generally linear with the second teeth or serrations32 being curved or serpentine.

Although not shown, it should be appreciated that the embodiments shownin FIGS. 6, 7, 8A-8B, 9A-9B and 11 could be provided such that they arecontinuous and uninterrupted or discontinuous and interrupted. Likewise,the teeth illustrated in the figures could be provided such that thefirst and second pluralities of teeth or serrations 26 and 32 in theembodiments are not of the same cross-sectional dimension or shape. Asmentioned earlier relative to FIG. 11, it should be understood that theindividual tooth 26 and 32 could be adapted or provided so that they areneither regular nor symmetrical when viewed in one or more of thedirections in arrow B, arrow C or arrow D in FIGS. 1-1A. Thus,individual teeth of both the first plurality of teeth or serrations 26and the second plurality of teeth or serrations 32 could have differentpitches, depths, widths and the like.

Referring now to the embodiment shown in FIGS. 4, 5, 10A and 10B, thesecond or secondary area, layer or feature 28 may be provided in theform of a deposit or coating 40. As with prior embodiments, those partsthat are the same or similar to the parts shown in FIGS. 1-1A areidentified with the same part number except that prime marks (“′″”) hasbeen added to the part numbers in FIGS. 4 and 5 and a mark (“VI”) hasbeen added to those parts in the embodiment of FIGS. 10A and 10B. Asmentioned earlier, the second or secondary friction area, layer orfeature 28′″ coating or deposit 40′″ could be deposited onto, sprayedonto, melted onto or otherwise applied to the first or primary area,layer or feature 24′″. In the illustration being described relative toFIGS. 4 and 5, the coating 40′″ comprises a plurality of particles 42′″that are deposited onto, adhered to or otherwise applied to surfaces 12a 1′″, 12 a 2′″, 12 b 1′″ and 12 b 2′″. In this embodiment, the coating40′″ is applied using a plasma layer deposition

In this regard, the body 12′″ defines the orthopedic implant 10′″ forimplanting into the patient. The first or primary area, layer or feature24′″ in this embodiment is similar to the embodiment in FIGS. 1-1A inthat each surface 12 a 1′″, 12 a 2′″, 12 b 1′″ and 12 b 2′″ has ordefines a plurality of teeth or serrations 26′″. In the illustrationbeing described, each of the plurality of teeth or serrations 26′″comprises a first surface 26 e′″ (FIG. 4) and the second surface 26 f′″as shown having the coating or deposit 40′″ of particles 42′″. Note alsothat areas or surfaces 12 a 3′″, 12 a 4′″, 12 b 3′″ and 12 b 4′″ (FIG.5) also have the coating or deposit 40′″ of particles 42. In theillustration being described, the coating or deposit 40′″ is titanium,cobalt or associated alloys. As previously mentioned, the teeth orserrations 26 may be asymmetrical to enhance frictional engagement.

Thus, each of the ends 12 a′″ and 12 b′″ in the illustration beingdescribed comprise the coating or deposit 40′″ of particles 42′″. In theillustration shown in FIGS. 4 and 5, note that the layer or coating 46′″is continuous over the first or primary area, layer or feature 24′″ andon ends 12 a′″ and 12 b′″, but it should be understood that the ends 12a′″ and 12 b′″ could be spot coated, and less than the entire first orprimary area, layer or feature 24′″ may have no deposit or coatingthereon. This is illustrated in FIGS. 10A-10B where some of the areas ofthe first teeth or serrations 26, such as the areas 50, may not comprisethe deposit or coating as shown. Stated another way, the coating 40^(VI) or deposit 40′″ may be selectively provided or applied to thosesurfaces of the orthopedic implant 10′″ that engage bone.

In the embodiment of FIG. 7, the surfaces, such as surfaces 32 b ^(VII)and 32 c ^(VII) of each of the second plurality of teeth or serrations32 ^(VII) comprises a deposit or coating or deposit 40 ^(VII) ofparticles 42 ^(VII) similar to that shown in FIG. 5. Thus, it should beunderstood that the embodiment shown in FIGS. 4 and 5 illustrates thesecond or secondary area, layer or feature 28′″ comprising the depositor coating as shown, whereas the embodiment illustrated in FIG. 7 showsthe first or primary area, layer or feature 24 ^(VII) having the firstplurality of teeth or serrations 26 ^(VII) having the second orsecondary area, layer or feature 28 ^(VII) in the form of the secondplurality of teeth or serrations 32 ^(VII) which themselves have thecoating or deposit 40 ^(VII) of particles 42 ^(VII).

In the illustrations being described, any particles 42 ^(VII) that areapplied, sprayed, adhered, coated, deposited or melted onto at least oneof the first or primary area, layer or feature 24 ^(VII) or the secondor secondary area, layer or feature 28 ^(VII) may be round, not round orcircular or non-circular, coarse, acyclic, and may form a continuouslayer or discontinuous or discreet layer on all or only a portion of thefirst or primary area, layer or feature 24 ^(VII) or the second orsecondary area, layer or feature 28 ^(VII). As mentioned earlier, thefirst or primary area, layer or feature 24 ^(VII) and the second orsecondary area, layer or feature 28 ^(VII) may be comprised of the samesubstance or material or they could comprise different materials, suchas a metallic or metallic alloy as mentioned earlier herein, or athermal plastic such as PEEK. In the illustration of FIGS. 4, 5, 7 and10A-10B, the layer or coating 46′″ is a metallic coating of titanium,cobalt or associated alloys deposited on the first plurality of teeth orserrations 26′″ using plasma vapor deposition.

Advantageously, the second or secondary area, layer or feature in allembodiments augments at least a portion or all of the external first orprimary area, layer or feature, such as the surfaces 26 a, 26 b of theone or more of the first plurality of teeth or serrations 26 in theembodiment of FIGS. 1-3 in order to enhance or add high friction to theengagement surfaces of the orthopedic implant 10. While traditionalimplants have engagement surfaces that engage bone, the embodimentsdescribed herein improve the frictional engagement between the bone andthe orthopedic implant 10 by adding the second or secondary area, layeror feature 28 which provides improved frictional engagement between thefrictional surfaces of the orthopedic implant 10 and bone.

Advantageously, one advantage of the orthopedic implant 10 as describedherein is that it improves the inherently low levels of bone-orthopedicimplant 10 interface and surface interaction. The primary frictionalfeatures described herein add a surface material, such as a metallicsurface material, to the first or primary friction area, layer orfeature 24 which provides low lubricity, low elasticity and thesecondary frictional features defined by the second or secondaryfriction area, layer or feature 28. The embodiments described provide orcomprise a design that will maintain the biomechanical properties of theorthopedic implant 10 while addressing frictional shortcomings of theorthopedic implant 10 and the interfaces between the bone and theimplants of the past.

While the system, apparatus and method herein described constitutepreferred embodiments of this invention, it is to be understood that theinvention is not limited to this precise system, apparatus and method,and that changes may be made therein without departing from the scope ofthe invention which is defined in the appended claims.

1. An orthopedic implant comprising: a substrate material adapted toprovide the orthopedic implant; a primary friction area located on orintegral with said substrate material, said primary friction area havinga primary surface having a primary frictional feature; and a secondaryfriction area located on or integral with said primary surface anddefining a secondary frictional feature; said primary friction area andsaid secondary friction area defining a friction interface zone, saidsecondary friction area increasing a friction of said primary surface toenhance the frictional engagement between said primary surface and atleast one bone.
 2. The orthopedic implant as recited in claim 1 whereinsaid primary friction area having a primary friction surface that is atleast one of machined, molded, extruded, sintered or depositedsubstrate.
 3. The orthopedic implant as recited in claim 2 wherein saiddeposited substrate is a polymeric substrate.
 4. The orthopedic implantas recited in claim 2 wherein said primary friction surface defines aplurality of teeth or serrations.
 5. The orthopedic implant as recitedin claim 4 wherein said secondary friction area that is at least one ofmachined, molded, extruded, sintered or deposited substrate.
 6. Theorthopedic implant as recited in claim 4 wherein said secondary frictionarea comprises at least one of a microscopically or macroscopicallyrough surface.
 7. The orthopedic implant as recited in claim 1 whereinsaid secondary friction area is regular in shape.
 8. The orthopedicimplant as recited in claim 1 wherein said secondary friction area isirregular in shape.
 9. The orthopedic implant as recited in claim 1wherein said substrate material is made from a thermoplastic.
 10. Theorthopedic implant as recited in claim 9 wherein said thermoplastic is apolyetheretherketone (PEEK).
 11. The orthopedic implant as recited inclaim 1 wherein a modulus of elasticity of said substrate material isless than or equivalent to bone.
 12. The orthopedic implant as recitedin claim 11 wherein said substrate material has a low coefficient offriction with bone.
 13. The orthopedic implant as recited in claim 1wherein at least one of said primary friction area or said secondaryfriction area being made from a metal or metallic alloy.
 14. Theorthopedic implant as recited in claim 1 wherein at least one of saidprimary friction area or said secondary friction area having a modulusof elasticity that the same as or greater than bone.
 15. The orthopedicimplant as recited in claim 11 wherein said at least one of said primaryfriction area or said secondary friction area having a modulus ofelasticity that the same as or greater than bone.
 16. The orthopedicimplant as recited in claim 1 wherein at least one of said primaryfriction area or said secondary friction area comprising a highercoefficient of friction with bone.
 17. The orthopedic implant as recitedin claim 1 wherein at least one of said primary friction area or saidsecondary friction area having a modulus of elasticity that the same asor greater than bone.
 18. The orthopedic implant as recited in claim 1wherein said primary friction area comprising a higher coefficient offriction with bone and said secondary friction area comprising a highercoefficient of friction than said primary friction area.
 19. Theorthopedic implant as recited in claim 1 wherein said primary frictionarea having a modulus of elasticity that the same as or greater thanbone and said secondary friction area having a modulus of elasticitythat is the same or greater than said primary friction area.
 20. Theorthopedic implant as recited in claim 1 wherein said secondaryfrictional feature is integral with, welded to, adhered to or otherwiseaffixed to said primary frictional feature.
 21. The orthopedic implantas recited in claim 1 wherein said secondary frictional feature issprayed onto, melted to or applied to said primary friction area. 22.The orthopedic implant as recited in claim 21 wherein said secondaryfrictional feature are defined by particles that are at least one ofround, not round or acicular, circular, coarse, acyclic.
 23. Theorthopedic implant as recited in claim 22 wherein said particles arecontinuous or discontinuous or discrete on at least a portion of saidprimary frictional feature.
 24. The orthopedic implant as recited inclaim 1 wherein said secondary frictional feature defines a plurality ofteeth, points or peaks on said primary friction area.
 25. The orthopedicimplant as recited in claim 24 wherein said plurality of teeth, pointsor peaks are neither regular nor symmetrical.
 26. The orthopedic implantas recited in claim 24 wherein said plurality of teeth, points or peaksare regular and symmetrical.
 27. The orthopedic implant as recited inclaim 1 wherein said primary frictional feature and said secondaryfrictional feature are made from different materials.
 28. The orthopedicimplant as recited in claim 1 wherein said primary frictional featureand said secondary frictional feature are made from the same materials.29. The orthopedic implant as recited in claim 1 wherein said at leastone of said primary frictional feature, said secondary frictionalfeature or said substrate material is made from a different materialthan the others.
 30. The orthopedic implant as recited in claim 1wherein said secondary frictional feature increases a coefficient offriction of said orthopedic implant and bone.
 31. The orthopedic implantas recited in claim 1 wherein said orthopedic implant is a spinalimplant.
 32. The orthopedic implant as recited in claim 31 wherein saidspinal implant is a cage.
 33. The orthopedic implant as recited in claim1 wherein said secondary frictional feature is a deposit onto saidprimary surface.
 34. The orthopedic implant as recited in claim 33wherein said deposit is a plasma vapor deposition deposit.
 35. Theorthopedic implant as recited in claim 33 wherein said primary surfacedefines a plurality of teeth or serrations and said deposit is appliedto surfaces of one or more of said plurality of teeth or serrations. 36.An orthopedic implant comprising: a body comprising a compositematerial; a first friction area situated between the body and bone of apatient when the orthopedic implant is implanted in the patient; and asecond friction area associated with said first friction area fordirectly engaging said bone, each of said first and second frictionareas for improving a frictional engagement between said bone and saidorthopedic implant.
 37. The orthopedic implant as recited in claim 36wherein said body and said first friction area comprise have a modulusof elasticity that is lower than a modulus of elasticity of said secondfriction area.
 38. The orthopedic implant as recited in claim 36 whereinsaid second friction area defines a frictional engaging surface thatincreases a coefficient of friction between said first friction area andsaid bone.
 39. The orthopedic implant as recited in claim 36 whereinbody is made from a polymeric material, and at least one of said firstor second friction areas comprises a metallic or metallic alloy.
 40. Theorthopedic implant as recited in claim 38 wherein said first frictionarea defines a plurality of teeth or serrations and said second frictionarea defines a layer or coating thereon.
 41. The orthopedic implant asrecited in claim 40 wherein said second friction area is at least one ofmachined, molded, extruded, sintered or deposited substrate.
 42. Theorthopedic implant as recited in claim 40 wherein said second frictionarea comprises at least one of a microscopically or macroscopicallyrough surface.
 43. The orthopedic implant as recited in claim 36 whereinsaid second friction area is uninterrupted.
 44. The orthopedic implantas recited in claim 36 wherein said second friction area is irregular inshape.
 45. The orthopedic implant as recited in claim 36 wherein saidcomposite material is made from a thermoplastic.
 46. The orthopedicimplant as recited in claim 45 wherein said thermoplastic is apolyetheretherketone (PEEK).
 47. The orthopedic implant as recited inclaim 36 wherein a modulus of elasticity of said composite material isless than or equivalent to bone.
 48. The orthopedic implant as recitedin claim 47 wherein a coefficient of friction associated with saidcomposite material and bone is lower than a coefficient of frictionbetween said second friction area and said bone.
 49. The orthopedicimplant as recited in claim 36 wherein each of said first friction areaand said second friction area are made from a metal or metallic alloyand said body is made of a polymer.
 50. The orthopedic implant asrecited in claim 36 wherein each of said first friction area or saidsecond friction area have a modulus of elasticity that is the same as orgreater than bone.
 51. The orthopedic implant as recited in claim 47wherein each of said first friction area and said second friction areacomprise a higher coefficient of friction with bone.
 52. The orthopedicimplant as recited in claim 36 wherein said second friction area isintegral with, welded to, adhered to or otherwise affixed to said firstfriction area.
 53. The orthopedic implant as recited in claim 36 whereinsaid second friction area is sprayed onto, melted to, adhered to orapplied to said first friction area.
 54. The orthopedic implant asrecited in claim 53 wherein said second friction area is defined byparticles that are at least one of round, not round, circular, coarse,acyclic.
 55. The orthopedic implant as recited in claim 54 wherein saidparticles are continuous or discontinuous or discrete on at least aportion of said first friction area.
 56. The orthopedic implant asrecited in claim 36 wherein said second friction area defines aplurality of points or peaks on said first friction area.
 57. Theorthopedic implant as recited in claim 56 wherein said plurality ofpoints or peaks are neither regular nor symmetrical.
 58. The orthopedicimplant as recited in claim 56 wherein said plurality of points or peaksare regular and symmetrical.
 59. The orthopedic implant as recited inclaim 36 wherein said orthopedic implant is a spinal implant.
 60. Theorthopedic implant as recited in claim 59 wherein said spinal implant isa cage.
 61. The orthopedic implant as recited in claim 36 wherein saidsecond friction area is a deposit onto said first friction area.
 62. Theorthopedic implant as recited in claim 61 wherein said deposit is aplasma vapor deposition deposit.
 63. The orthopedic implant as recitedin claim 61 wherein said first friction area defines a plurality ofteeth or serrations and said deposit is applied to surfaces of one ormore of said plurality of teeth or serrations.
 64. A method forimproving a frictional interface between an implant and bone of apatient, comprising the steps of: processing a body to comprise aprimary friction feature, and processing said body to comprise asecondary friction feature directly on said primary friction feature.65. The method as recited in claim 64 wherein said primary frictionfeature has a primary friction surface that is at least one of machined,molded, extruded, sintered or deposited substrate.
 66. The method asrecited in claim 65 wherein said least one of machined, molded,extruded, sintered or deposited substrate is a polymeric substrate. 67.The method as recited in claim 65 wherein said primary friction surfacedefines a plurality of teeth or serrations.
 68. The method as recited inclaim 64 wherein said secondary friction feature that is at least one ofmachined, molded, extruded, sintered or deposited substrate.
 69. Themethod as recited in claim 64 wherein said secondary friction featurecomprises at least one of a microscopically or macroscopically roughsurface.
 70. The method as recited in claim 64 wherein said secondaryfriction feature is regular in shape.
 71. The method as recited in claim64 wherein said secondary friction feature is irregular in shape. 72.The method as recited in claim 65 wherein said least one of machined,molded, extruded, sintered or deposited substrate has a low coefficientof friction with bone.
 73. The method as recited in claim 65 wherein atleast one of said primary friction surface or said secondary frictionfeature being a deposit on said primary friction surface of a metal ormetallic alloy.
 74. The method as recited in claim 65 wherein saidsecondary friction feature defines a plurality of teeth, points or peakson said primary friction surface.
 75. The method as recited in claim 64wherein said method comprises the step of: depositing said secondaryfriction feature onto said primary friction feature.
 76. The method asrecited in claim 75 wherein said depositing step is performed usingplasma vapor deposition.